There is known a cooling structure of an in-wheel motor for cooling an in-wheel motor unit, where a motor unit is included to an inner region of a road wheel, an inverter is disposed internally and coaxially in the vehicle width direction, and a heat conducting member is arranged to the motor unit. In the cooling structure, an extension part that extends downward is formed to the heat conducting member and by receiving travelling wind by the extension part during vehicle travelling, the extended part functions as a heat dissipation member (Patent Document 1).